Dishwashing machine



Nov. 8, 1960 R. M. SASNETT ETAL 2,959,179

DISHWASHING MACHINE 3 Sheets-Sheet 1 Filed July 10 1957 IN V EN TORS RUSSELL M. SASNETT 8 LAUREN w. GUTH flunk THEIR ATTORNEY Nov. 8, 1960 R. M. SASNETT ETAL 2,959,179

DISHWASHING MACHINE Filed July 10. 1957 s- Sheets-Sheet 2 F'IG.3

INVENTORS usszm. M. SASNETT 8 LAUREN w. eu'rn THEIR ATTORNEY Nov. 8, 1960 R. M. SASNETT ETAL 2,959,179

DISHWASHING MACHINE Filed July 10. 1957 3 Sheets-Sheet 3 F'IG.6

INVENTORS ausssu. M. sAsma'r'r E, LAUREN w. GUT H THEIR ATTORNEY United States Patent O DISHWASHING MACHINE Russell M. Sasnett, Louisville, Ky., and Lauren W. Guth,

Springfield, Pa., assignors to General Electric Company, a corporation of New York Filed July 10, 1957, Ser. No. 671,070

7 Claims. (Cl. 134-186) This invention relates to dishwashing machines, and more particularly to a dishwasher having improved water circulating and tub draining means adapted to reduce soft or semi-solid food wastes to small particle size and discharge such food particles from the tub with the washing fluid.

Dishwashers of the domestic type on the market and in use at the present time are generally designed to employ an operating cycle which includes a series of separate washing and rinsing operations in each of which a relatively small quantity of water is admitted to the washing compartment, circulated for a short period of time, and then discharged from the machine. In addition to a water inlet control device and water circulating means, a drain control system is evidently required if the operating cycle just described is to be performed automatically, and in a number of presently known dishwashers a mechanical drain valve arranged to control flow in a drain line connected to the bottom of the washing compartment is provided for this purpose. In such machines, the drainage system may include a drain pump or it may be arranged so as to drain by gravity.

In another known dishwashing machine a centrifugal pump is employed to prevent flow of washing fluid from the washing compartment during each washing and rinsing operation, drainage being accomplished by stopping the pump so as to permit flow through the pump chamber.

In still another known arrangement, a baffle including restricted flow directing openings is associated with a centrifugal pump in such a way that the pump prevents drainage when rotating in one direction and provides a positive discharge pressure when rotating in the other direction. While these prior art systems have certain advantages, none are particularly suited for use in a dishwasher adapted to remove substantially all. soft or semisolid food waste found on dishes at the end of a meal, because both the mechanical valve and the centrifugal pump arrangements have restricted openings which may become clogged by such waste material. Because dishwashers of the type described above are not capable of efiiciently disposing of soft food wastes, manufacturers instructions for operation of such dishwashers commonly recommend fairly thorough hand scraping and rinsing of all dishes before placement in the dishwashing compartment.

It is a general object of the present invention to provide a dishwasher including a washing and drainage system adapted to remove and discharge with the washing fluid a substantial portion of the soft food wastes found on dishes at the end of a meal, so as to minimize preliminary hand scraping and rinsing operations.

Another object of this invention is to provide a dishwasher including washing mechanism adapted to pulverize semi-solid food wastes and a drainage system adapted to discharge washing fluid and entrained food particles.

Another object of this invention is to provide a dishwashing machine including a valveless drainage system r. 2,959,179 Patented Nov. 8, 1960 having a rotary drain pump with an unobstructed axial inlet and an impeller adapted to supply a positive discharge pressure in one direction of rotation and substantially no discharge pressure in the drain line when rotating in the opposite direction.

Still another object of this invention is to provide a dishwasher including a wash impeller and a drain pump impeller mounted on a common reversible motor shaft and arranged so that water is circulated in the washing compartment and the pump impeller produces equal and opposed pressure components when the shaft rotates in one direction, and in the opposite direction of rotation the pump provides a positive discharge pressure.

Further objects and advantages of this invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly stated, in accordance with one aspect of this invention there is provided in a dishwasher of the type in which a series of separate washing and rinsing operations constitute a complete washing cycle, a drain pump having a large axial inlet opening and a rotary impeller cooperating with the pump housing structure so as to provide a positive discharge pressure when rotating in one direction, and a discharge pressure component which is substantially balanced and neutralized by an opposed pressure component when rotating in the opposite direction, whereby both the pump impeller and rotary water circulating impeller means located in the dishwashing compartment may be operated by a common shaft driven by a reversible motor. Thus during each washing and rinsing operation the motor drives both impellers in the last mentioned direction so as to circulate water in the washing compartment and remove semi-solid food waste from the dishes therein, and the motor is then reversed so as to drive the pump impeller in the direction which results in a positive pressure. Since no discharge pressure is produced in the drain line of the pump during the washing periods, the need for a drain valve is eliminated and it is only necessary to position a portion of the drain line above the highest static water level in the washing compartment. Inasmuch as the drain pump impeller is the only obstruction in the entire drainage system, and since this member functions to break up semi-solid food particles and is also inherently self-cleaning it will 'be seen that this arrangement is particularly suited for the discharge of washing fluid and entrained soft food waste particles.

For a better understanding of this invention, reference may be madeto the following description'and accompanying drawings in which:

Fig. 1 is a front elevation view, with some of the parts being broken away to show details of construction, of a dishwasher incorporating the present invention.

Fig. 2 is an enlarged fragmentary elevation view of a portion of the dishwasher shown in Fig. 1.

Fig. 3 is a sectional view taken on the line 3--3 in Fig. 2, some of the parts being broken away.

Fig. 4 is. a fragmentary sectional view taken along the lines 4-4 in Fig. 3.

Fig. 5 is a side elevation view of the wash impeller shown in Fig 2.

Fig. 6 is a top plan view'of the impeller.

Fig. 7 is a sectional view taken along the line 7-7 in Fig. 6.

Fig. 8 is a sectional view taken along the line 8-1-8 in Fig. 6.

Referring to Fig. l of the drawing, there isshown a dishwasher having an enclosed washing compartment or tub l'of generally rectangular configuration, in which to support dishes or the like during washing operations. The dishwasher is provided with a water inlet valve 5 adapted to be connected to a water supply system, a water inlet conduit 6, and a fill funnel 7 communicating with the interior of tub 1, these Components being mounted on the front wall of the tub and enclosed by a front panel 8. Tub 1 has a generally conical bottom wall 2 and a top access opening which is closed by a hinged top cover 9 during Washing operations, being held in closed position by a latch mechanism 10 which includes an interlock arrangement mechanically associated with a sequence control device or timer generally designated by the numeral 10a.

In accordance with the present invention a drain pump 11 is supported beneath tub 1, pump 11 having an axial, and preferably circular inlet opening 12 communicating with the tub,.an outlet 13 connected to drain conduit 14, and a housing arranged to support a reversible electric motor 16. It will of course be understood that conduit 14 is adapted to be connected to a plumbing drainage system, and that the conduit extends above the maximum static water level in tub I (which is below rack 4). Thus water entering the tub is retained therein until discharged by pump 11. Housing 15 is preferably formed of rubber or plastic material and may be reinforced by an outer sheet metal shell including a cylindrical portion 17 and a bottom portion 18. Motor 16 is provided with a plurality of mounting studs 19 fixedly secured thereto and arranged to be supported on projecting portions 20 of lower shell 18. Preferably, resilient vibration dampeners 21 are provided between supporting portion 20 of the lower shell and clamp 22. Pump ll is secured to the bottom wall 2 of tub I by a pair of semi-circular clamps '23 and 24 which cooperate with flange portion 25 of the pump housing and an annular flange 26 which is fixedly secured to the tub wall 2. It will be observed that a portion of flange 26 is interlocked with a bent-over annular portion of tub 2 forming circular inlet opening 12, and that the circular opening 12 is smaller than the diameter of the pump chamber formed by housing 15.

Shaft 27 of motor 16 projects upwardly through pump housing 15 and supports both a pump impeller 28 and a washing impeller 29 for rotation therewith. Pump im peller 28 includes a disk shaped portion 30, a recessed portion 31 in which is housed a shaft sealing element 32 and a tubular portion 33 fixedly secured to shaft 27. Formed integrally with disk shaped portion of pump impeller 28 are a plurality of blades 34 lanced downwardly from the plane of disk portion 30 to form a narrow slit adjacent each blade. Each blade having an angle substantially less than 90 degrees along a line extending generally radially from central portion 31 of the impeller to the periphery thereof, but inclined forwardly with respect to clockwise rotation of the impeller, as viewed in Fig. 3. It will be noted that blades 34 rotate in a path adjacent the upper edge of discharge outlet 13, and that impeller 28 rotates about the axis of circular opeiiizng 12, which coincides with the axis of conical wa As shown in Fig. 2, the diameter of pump impeller 28 is substantially greater than the diameter of pump inlet opening 12, and therefore impeller 28 provides centrifugal pumping action in both directions of rotation. Because blades 34 are bent at an angle of substantially less than 90 degrees (for example, approximately 60 degrees) from the plane of disk shaped portions 30 and are curved as shown in Fig. 4 they provide an upward axial force component when the impeller is rotating in the clockwise dlrection and thus when the pump 11 is operating in this manner the centrifugal and axial force components impgted to water entering the pump chamber oppose each 0 er.

It will be understood that the centrifugal force component of the fluid-moving force in pump 11 during rotatron of impeller 28 is a function of 16 iQ of diameter of the impeller to the diameter of inlet opening 12, and that the axial force component of the fluid-moving force is a function of the shape and size of blades 34. In accordance with the present invention the diameters of circular inlet opening 12 and pump impeller 28 are so porportioned in relation to the shape of impeller blades 34 that these axial and centrifugal force components are substantially equal, and hence substantially no discharge pressure is produced in drain conduit 14 when impeller 28 rotates in the clockwise direction, as viewed in Fig. 3, because these forces then oppose each other. In some instances it may be desirable to proportion the dimensions of the pump elements so that a slight positive pressure (1 or 2 inches of water, for example) is produced when the pump impeller rotates in the clockwise direction, to avoid the creation of negative or suction pressure in the drain line. On the other hand, when the pump impeller rotates in the counter-clockwise direction a downward axial force is produced, and the axial and centrifugal force components are additive so as to produce a substantial discharge pressure in drain conduit 14, so that water in tub 2 is quickly pumped out throu h conduit 14 when motor 16 is reversed after a washing operation.

From the foregoing description it will be evident that there is no necessity for locating a drain valve in conduit 14 since the desired quantity of water may be retained in tub I by arranging a portion of conduit 14 above the desired static water level in the tub. Furthermore, it should be noted that the drainage passage from tub I to the outlet 'of drain conduit 14 is obstructed only by pump impeller 28 and inasmuch as the impeller includes numerous relatively sharp edges capable of breaking up solid food particles and because the impeller is inherent 1y self cleaning since it rotates at high speed, it will be seen that this drainage arrangement is particularly suited for the discharge of soft food waste particles entrained in the washing fluid.

Wash impeller 29 is preferably formed of sheet metal; such as stainless steel and is arranged to be mounted on motor shaft 27. As illustrated in Fig. 2, impeller 29 is fixedly secured to a tubular shaft 35 which is fixedly engaged with tubular member 33 of pump impeller 28. The upper end of tubular shaft 35 includes an integral T-shaped portion adapted to receive a pair of screws 36 and 37 which fasten impeller 29 for rotation with impeller .28 and motor shaft 27. Impeller 29 in cludes a pair of diametrically opposed blades which are arranged to circulate water or washing fluid within tub I when the impeller rotates in the clockwise direction, as viewed in Fig. 3. Both blades have the same but opposite configuration and include a sharpened leading edge portion 39 of plow shape generally parallel to bottom wall 2 of the tub, a trailing edge portion 40 substantially perpendicular to bottom wall 2, a concave top surface, and a convex bottom surface, the blades being relatively low in overall height and proportioned in relation to the shape and capacity of tub I so as to provide a regulated constant volume spray of water throughout the tub. In the preferred embodiment of the invention, the maximum vertical distance between leading edge 39 and trailing edge 40 is less than the maximum horizontal distance between these edges, and the same horizontal distance is less than the radial extent of the blades. As mentioned above, wash impeller 38 functions to circulate a spray of water throughout the dishwashing compartment when rotating in the clockwise direction, this being the direction in which pump impeller 28 does not produce appreciable discharge pressure in conduit 14. When rotating in the counter-clockwise direction, wash impeller 29 imparts only radial and downward movement to water contained in tub 1, whereby water in the tub is permitted to accumulate on bottom wall 2 and flow into pump 11 where the centrifugal and axial pressure compglleuts resulting from counterclockwise rotation of pump impeller 28 produce a positive pressure head suffi, cient to rapidly pump all of the Water out of tub 1 into discharge conduit 14.

In a complete washing cycle, it will be understood that time a controls the energization of solenoid valve 5 and motor 16 in a predetermined sequence, which may include two preliminary rinsing operations, a washing operation, and three final rinsing operations, for example. Thus at the beginning of the cycle, valve 5 is opened for a short time interval so as to admit a predetermined quantity of water and motor 16 is energized so as to rotate wash impeller 29 and pump impeller 28 in the clockwise direction, as viewed in Fig. 3, whereby the water entering the tub is circulated throughout the washing compartment. After a short period of time, as determined by timer 10a, motor 16 is reversed, and the initial charge of water is pumped out through drain conduit 14. This sequence of steps is repeated during subsequent rinsing and washing operations, it being understood that a quantity of detergent may be automatically deposited in the tub by suitable means (not shown) at the beginning of the washing operation. 7

While we have shown and described a particular embodiment of our invention, we do not desire the invention to be limited to the particular construction disclosed, and we intend by the appended claims to cover all modifications within the true spirit and scope of our invention.

What is claimed is:

1. A dishwasher comprising a tub forming a washing compartment, a wash impeller mounted in said tub for rotation on a vertical axis, said wash impeller including blade members for circulating water throughout said washing compartment when said wash impeller is rotated in a first direction, said blade members having a concave top surface and a convex bottom surface considered with respect to rotation in said first direction, a pump housing including a bottom wall and a generally cylindrical side wall defining a pump chamber at the bottom of said tub below said wash impeller, a wall member forming a circular ledge overhanging said pump chamber and defining a large non-clogging circular inlet opening between said tub and said pump chamber generally concentric with said axis and large enough to be capable of handling the discharge of washing fluid and entrained soft food waste particles, said pump housing having a discharge opening therein located in said cylindrical wall adjacent to the lower edge thereof, a discharge conduit connected to said discharge opening, a pump impeller fixedly secured to said wash impeller disposed in said chamber above said discharge opening for rotation about said axis, said pump impeller including a circular disk shaped portion of greater diameter than the diameter of said inlet opening and a plurality of blades integral with said disk shaped portion, each of said blades being bent downwardly from the plane of said disk shaped portion at an angle substantially less than ninety degrees along a line extending generally radially from the central part of said disk shaped portion to the periphery thereof but inclined forwardly with respect to said first direction of rotation, said blades being shaped so as to impart to water entering said pump chamber substantially equal axial and centrifugal force components which oppose each other and prevent drainage by returning the water to the tub when said pump impeller is rotated in said first direction, said force component being additive so as to produce a positive discharge pressure and drain off the water when said pump impeller is rotated in a second direction opposite to said first direction, and a reversible motor for driving said impellers.

2. A dishwasher comprising a tub having side walls and a generally conical bottom wall forming a washing compartment, means for admitting water to said tub, drain means for controlling the discharge of water from said tub, and a wash impeller mounted in said tub adjacent said bottom wall for rotation about the axis of said conical wall, said impeller including a pair of diametricali 1y opposed sheet metal blades each having a sharpened leading edge portion generally parallel to said bottom wall, a concave top surface bounded by said leading edge and a trailing edge portion substantially perpendicular to said bottom wall, the maximum vertical distance between said leading edge portion and said trail ing edge portion being less than the maximum horizontal distance between said portions, and said horizontal distance being less than the radial extent of said blades.

3. A dishwasher comprising a tub forming a washing compartment, means for circulating water Within said compartment, a pump housing adjacent the bottom wall of said tub including a generally cylindrical side wall defining a pump chamber, said bottom wall having a circular opening therein overlying said pump chamber so as to provide an inlet thereto that is large enough to be capable of handling the discharge of washing fluid and entrained soft food waste particles, the edge of said opening being concentric with said side wall, a discharge conduit connected to a discharge opening in said housing, a pump impeller disposed in said pump chamber for rotation about the axis of said cylindrical side wall, said pump impeller including a circular disk shaped portion of sufliciently large diameter that its periphery'underlies said bottom wall and only its central portion is directly below said pump chamber inlet opening, and a plurality of blades integral with said disk shaped portion, each of said blades being bent downwardly from the plane of said disk shaped portion at an angle substantially less than ninety degrees along a line extending generally radially from the central part of said disk shaped portion, said blades being shaped so as to impart to water entering said pump chamber substantially equal axial and centrifugal force components which oppose each other and prevent drainage by returning the water to the tub when said pump impeller is rotated in a first direction and which are additive so as to produce a positive discharge pressure when said pump impeller is rotated in a second direction opposite to said first direction.

4. A dishwasher comprising a tub including side and bottom walls forming a washing compartment, means for circulating water within said compartment, a pump housing including a bottom wall and a generally cylindrical side wall defining a pump chamber, said pump housing being secured to the lower side of the bottom wall of said tub, said bottom wall of said tub having a circular opening therein overlying said pump chamber so as to provide an inlet thereto that is large enough to be capable of handling the discharge of washing fluid and entrained soft food waste particles, the edge of said opening being concentric with said side wall, said pump housing having a discharge outlet therein, a pump impeller disposed in said pump chamber for rotation about the axis of said side wall, said pump impeller including a central portion underlying said opening and a peripheral portion underlying said bottom wall of said tub, a plurality of blade members secured to the peripheral portion of said pump impeller, said blade members being shaped so as to impart to water entering said pump chamber substantially equal axial and centrifugal force components which oppose each other and prevent drainage by returning the water to the tub when said pump impeller is rotated in a first direction and which are additive so as to produce a postive discharge pressure when said pump impeller is rotated in the opposite direction.

5. A dishwasher comprising a tub forming a Washing compartment, a wash impeller mounted in said tub for rotation on a vertical axis, said washer impeller including first bl-ade members for circulating water throughout said washing compartment when said wash impeller is rotated in a first direction, a pump housing including a bottom wall and a generally cylindrical side wall concentric with said axis defining a pump chamber atvthe bottom of said tub below said wash impeller, said tub including a bottom wall member having a circular opening therein overlying said pump chamber so as to provide an inlet thereto that is large enough to be capable of handling the discharge of washing fluid and entrained soft food waste particles, the edge of said opening being concentric with said side wall, said pump housing having a discharge outlet therein, a pump impeller disposed in said pump chamber for rotation about said axis, said pump impeller including a central portion underlying said opening and a peripheral portion underlying said bottom wall member, a plurality of second blade members secured to the peripheral portion of said pump impeller, said second blade members being shaped so as to impart to water entering said pump chamber substantially equal axial and centrifugal force components which oppose each other and prevent drainage by returning the water to the tub when said pump impeller is rotated in a first direction and which are additive so as to produce a positive discharge pressure when said pump impeller is rotated in the opposite direction, and means including a shaft fixedly secured to said impellers for selectively rotating said impellers in said first direction or said opposite direction.

' 6. A dishwasher comprising a tub forming a'washing compartment, a wash impeller mounted in said tub for rotation on a vertical axis, said wash impeller including first blade members for circulating water throughout said washing compartment when said wash impeller is rotated in a first direction, a pump housing including a bottom wall and a generally cylindrical side wall concentric with said axis defining a pump chamber at the bottom of said tub below said wash impeller, said tub including a bottom wall member having a circular opening therein overlying said pump chamber so as to provide an inlet thereto that is large enough to be capable of handling the discharge of washing fluid and entrained soft food waste particles, the edge of said opening being concentric with said side wall, said pump housing having a discharge outlet therein, a pump impeller disposed in said pump chamber for rotation about said axis, said pump impeller including a central portion underlying said opening and a peripheral portion underlying said bottom Wall member, a plurality of second blade members secured to the peripheral por tion of said pump impeller, said second blade members being integral with said peripheral portion and bent downwardly from the plane thereof at an angle substantially less than ninety degrees along a line extending generally radially from said central portion, each of said blades being shaped so as to impart to water entering said pump chamber substantially equal axial and centrifugal force components which oppose each other and prevent drainage by returning the water to the tub when said pump impeller is rotated in a first direction and which are additive so as to produce a positive discharge pressure when said pump impeller is rotated in the opposite direction, and means including a shaft fixedly secured to said impellers for selectively rotating said impellers in said first direction or said opposite direction.

7. A dishwasher as recited in claim 2 wherein the leading edge of each blade of the wash impeller is plowshaped in plan view and forms at its outermost end a converging surface with respect to the trailing edge of the blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,707,475 Walker et a1. May 3, 1955 2,715,410 Ruspino Aug. 16, 1955 2,775,975 Andrews Jan. 1, 1957 

